function ajax(_method,_url,_data,_callback){
    let xhr=new XMLHttpRequest;

    xhr.open(_method,_url);

    xhr.send();

    xhr.addEventListener('readystatechange',function(){
        if(xhr.readyState ==4){
            if(xhr.status ==200){
                _callback(xhr.responseText)
            }else{
                
            }
        }
    })
}